The aim of the study is to determine whether the use of the CEST sequence would have diagnostic performance equivalent to the reference method of T2\* infusion with contrast injection in the diagnosis of radionecrosis of lung cancer brain metastases.
Patients > 18 years of age
Histologically proven primary lung cancer
Histologically proven or not brain metastases
Irradiated metastases
Opposition to the study
Contraindication to MRI
Refusal of imaging by the patient
Patient with state medical aid (unless exemption from affiliation)